
1. Sync sphinx dependency with global requirements. It caps python 2 since sphinx 2.0 no longer supports Python 2.7. 2. Update the UPPER_CONSTRAINTS_FILE for tox[1] 3. Update some URLs to latest [1]: http://lists.openstack.org/pipermail/openstack-discuss/2019-May/006478.html Change-Id: Ibe8c402c2817c31748e6a4b8344024a276609260